Photoelectron emission microscopy of ultrathin oxide covered devices

Abstract

Articles you may be interested inFabrication and characterization of metal-molecule-silicon devices Appl. Phys. Lett. 91, 033508 (2007); Trapping and detrapping of electrons photoinjected from silicon to ultrathin SiO 2 overlayers. I. In vacuum and in the presence of ambient oxygen Photoelectron emission microscopy ͑PEEM͒ has been used to investigate simple device structures buried under ultrathin oxides. In particular, we have imaged Au-SiO 2 and p-type Si-SiO 2 structures and have demonstrated that PEEM is sensitive to these buried structures. Oxide overlayers ranging up to 15.3 nm were grown by systematically varying the exposure time of the structures to a plasma-enhanced chemical-vapor deposition process. The change in image contrast as the oxide thickness increases was used to quantify the inelastic mean-free path of low-energy photoelectrons ͑ϳ1 eV͒ in amorphous silicon dioxide. For Au structures we find that the dominant mean-free path for photoelectrons in the overlying oxide is about 1.18Ϯ0.2 nm. Yet, we find a residual observable signal from the buried Au structure through roughly 13 oxide attenuation lengths. The signal attenuation from the Au can be explained by the spread of the photoelectron energies and the energy dependence of the electron-phonon interaction. Similar intensity attenuation behavior is also seen from heavily p-doped silicon (10 20 cm Ϫ3 ) regions, but the signal is only observable through roughly 3.0 nm of oxide, and the signal from the 10 18 cm Ϫ3 regions is not detectable through the thinnest oxide layer of approximately 2.5 nm. Here, the energy spread ͑ϳ2.0 eV͒ is more narrowly distributed about the phonon loss energies, leading to the observed attenuation behavior from heavily p-doped silicon.

Lateral straggling and its influence on lateral diffusion in implantation with a focused ion beam

“…Ga implantation into an n-type substrate would initially compensate and then transform the implanted region into p-type. p-type regions appear brighter in PEEM images [8,9]. Here a sharp stripe pattern is observed for implantation at RT (Fig.…”

“…The Ga concentration profile extends to the surface as the peak of the concentration profile is at a depth smaller than 3DR p . In any case, PEEM images can also be obtained from buried layers [9].…”

“…In the PEEM image p-doped Si regions appear brighter compared to n-doped regions [8]. Buried p-doped regions fabricated by broad beam implantation of boron (190 keV) into n-type silicon substrates also have shown brighter contrast in PEEM images from the B-implanted regions [9].…”

Recent Approaches for Bridging the Pressure Gap in Photoelectron Microspectroscopy

“…Development of such a PES-through-membrane approach is inspired by the successful photoelectron spectroscopy and microscopy of buried interfaces for a wide range of excitation energies spanning ultraviolet (UV) [23], soft X-rays [24] to hard X-rays [25,26]. The membrane can be considered as an overlayer with a thickness comparable to the IMFP, so that the signal from the immersed sample is directly related to the classical signal attenuation by overlayer films in surface science [27].…”

Study of Martensitic Phase Transformation in a NiTiCu Thin‐Film Shape‐Memory Alloy Using Photoelectron Emission Microscopy

“…1 eV) photoelectrons imaged in PEEM is 1-2 nm, resulting in excellent surface sensitivity. [35,36] PEEM intensities are sensitive to changes in the work function during phase transformations, as well as to changes in chemical composition, crystal orientation, and surface dipole. [37][38][39][40] In recent work, we described in situ PEEM observations of the phase transformation in bulk CuZnAl SMA.…”